This proposed work is principally aimed at serving as a resource for (1) continuation of studies in the herd of bleeder swine, which have been in progress at the University of Missouri for a number of years, and (2) to provide a national resource for utilization by other investigators of these bleeder swine for studies or for breeding purposes. These bleeder swine have a coagulation defect which mimics the human defect known as von Willebrand's Disease. This basically involves a variable level of deficiency in factor VIII in the coagulation mechanism, and also a modification of platelets typified by decreased platelet adhesiveness. Proposed studies in our own institution are aimed at an analysis of the biochemical, morphologic, and functional aspects of platelet defects in these animals and factors which stimulate factor VIII. Another major purpose of this program is to maintain a stock of animals, so that they may serve as a resource to investigators nationwide.